Lattice-truss.



PATENTED APR. 23, 19o?. J. o. MOKEOWN.

LATTICE Huss.

APPLICATION FILED FEB. 25, 1907.v

ency to buckle them laterally, it is obvious UNITED STATES PATENTOFFioE.

JOHN C. kMCKEOWN, OF CHICAGO, ILLINOIS.

LATTICE-reuse.

ySpecification of Letters Patent.

j ratentea April es, 1907.

v appunti@ iialrebrutry 28,1907. seriaiii. 359.295.-

Illinois, have invented certain new and use-l ful. Im rovements inLattice Trusses, of which t ie following is a specic'ation.

This invention relatesrtotrusses, such as roof and bridge trusses, andrelates particularly to lattice trusses of the familiar type comprisinga curved, usually substantially circular, upper chord, a. straight lowerchord andlcro'ssed lattice or web -members which connect said upper andlower chordsat in* tervals between their ends and .which are rigidlysecured together where they cross each other. In trusses of this type itis a simple engineering problem to figure out 'the -maximum and minimumtension and commembers willbe constructed, to make them adequatelystrongv to carry `their respective maximumloads. The lattice or webmembers, however, are usually larger in cross section in the plane ofthe truss than crosswise theretoL. and, vas compression stresses in saidlattice or web members willproduce a tendthat the capacity of saidlattice or web members to withstand the buckling stresses to which theyare subjected will determine the real vresistance or strength of thetruss as a whole. viously subjected to no buckling stress, and it'isalso obvious that the buckling stress in any compression member can belargely overcome by rigidly connecting it with the tension members whichit crosses, or by thus connecting crossed compression meinbers,-an

, averagebuckling stres produced therein.

The primary object f my invention is to provide a truss of this generaltype in which the lattice or web members will cross each other atrelatively short and substantially uniform intervals and in which eachlattice o`r web member will be crossed by a relatively i compressionstresses therein.

To this end, my invention consists in disposing' the lattice or webmembers of the A member, when in tension, is ob' l truss atsubstantially uniform angles to the upper or curved chord, sayforty-five degrees, instead 0f to the' lower, straight chord in themanner heretofore common.

A further object of the invention is to provide 'a ,composite top chordfor -a truss of this l type,lthe elements ofwhich will be rigidlyconnected throughout the length of said chord, whereby tthe elements ofsaid chord will be .flexedor bowed uniformly, thus maintaining the upperedge thereof, which receives the joists .ir other transverse supports,even throughout. To this end the elements of the top chord are providedwith interlocking longitudinal tongues and grooves, which 'operatein anobvious manner to cause said .elements to bend uniformly and to maintainthe ed es thereof even.

In't e accompanying drawing, in'v which my invention'ds fullyillustrated,-Figure 1 is a side view of a roof truss embodying myinvention; and Fig. 2 is an enlarged transverse sectional view of thetop chord thereof, showing lattice or web mem ers and a joist inelevatiom for purposes of concrete illustration, I have shown a truss ofm invention as applied for su orting a roof, represents the walls of a bding, B the roof thereof, comprising joistsb, and a covering b1, C theupper chor of the truss, D the lower chord thereof and E the lattice orweb members. Both theup er chord C and the lower chordD are refera lymade in two sections between Whic the ends of the lattice or web membersE are rigidly secured. a Each section of the curved top chord C consistsof a plurality of elements, as shown two elementsrl and 2, which aresecured together by longitudinal interlocking tongues 3 on one thereof,and ooves 4 on the other, which will cause said e ements 1 and 2 to benduniformly, so that the top ed es 5 thereof will be flush with each otheran will tice or web members E, instead ofibeing disppsed at a uniform ale to the lower chord are disposed at a uniform aigle, say fortyfivedegrees, to the top chord that is, to `a said lattice or we members arerespectively secured thereto. With the lattice or web members E dis osedat uniform angles to the top chord, as escribed, it is found that said`web members cross each other at substantially-uniformintervals, whereaswith the Referring novr to the drawings, in which,

ico

form-an even seatforthe joists b. The lattangent to said to chord at thepoints where IIO sitely inclined lattice or web member than in atrus'sfof the same size in which the lattice or web membersvare'disposed 'at the same angles to theA lowerj'chord. Thus bysecilringv the .saidjlattice or Web members together where they crosseach other, which may be done any desired manner as by means of bolts orspikes, it is obvious that the lattice orweb members fmy improved trussvvillbe supported against lateral buckling stresses atsubstantially'uniform intervals and at an in creased number'ofQin-ts,ufa's compared ,With asubstantially si a'r truss in which thelattice or web vmembers are disclosed at uniform angles tothelowerchord, thus effectin-g`the-gobject of feature.

Iclaimk- 1. A trussqcomprising 'a curved u per chord, a lowerychord andlattice memers which connect said chords, said lattice mem-1 bers beingdisposed at substantially uniform my invention `as relates'to thisangles to the ulpper chord at their respective polnts of attac unentthereto. u n

2. .A truss comprising a curved :upper chord, alwer chord and ,latticemembers which. connect said chords, said lattice members being disposedat angles of substantially fortyf-five degrees to the upper chord atthen' vrespective points of attachment thereto.

3.. A truss comprising a curved upper chord comprising a lurahty ofelements provided With longitudpinal interlocking tongues and grooves, alower chord and lattice members which connect said chords, said latticemembers being disposed at substantially unlform angles to the 'upperchord at thelr respective points of attachment thereto.'

4. Av truss comprising a curvedupper chord comprisingv a 'pluralityV ofelements provided with. longitudinal interlockmg tongues and grooves, avlower chord and lattice members Which connect said chords.

n :In testimony, that I claim the foregoing as *myy invention, I afiixmy signature 1n Lpres- AYVitnesses CHARLES B. GILLsoN, K. A.. COSTELLO.

